content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.internal.operators;
  
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.atomic.*;
  
  import io.reactivex.common.Disposable;
  import io.reactivex.common.exceptions.Exceptions;
  import io.reactivex.common.functions.Function;
  import io.reactivex.common.internal.disposables.DisposableHelper;
  import io.reactivex.common.internal.functions.ObjectHelper;
  import io.reactivex.observable.*;
  import io.reactivex.observable.Observer;
  import io.reactivex.observable.internal.disposables.EmptyDisposable;
  import io.reactivex.observable.internal.queues.SpscLinkedArrayQueue;
  
  public final class ObservableGroupBy<T, K, V> extends AbstractObservableWithUpstream<T, GroupedObservable<K, V>> {
      final Function<? super T, ? extends K> keySelector;
      final Function<? super T, ? extends V> valueSelector;
      final int bufferSize;
      final boolean delayError;
  
      public ObservableGroupBy(ObservableSource<T> source,
              Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector,
              int bufferSize, boolean delayError) {
          super(source);
          this.keySelector = keySelector;
          this.valueSelector = valueSelector;
          this.bufferSize = bufferSize;
          this.delayError = delayError;
      }
  
      @Override
      public void subscribeActual(Observer<? super GroupedObservable<K, V>> t) {
          source.subscribe(new GroupByObserver<T, K, V>(t, keySelector, valueSelector, bufferSize, delayError));
      }
  
      public static final class GroupByObserver<T, K, V> extends AtomicInteger implements Observer<T>, Disposable {
  
          private static final long serialVersionUID = -3688291656102519502L;
  
          final Observer<? super GroupedObservable<K, V>> actual;
          final Function<? super T, ? extends K> keySelector;
          final Function<? super T, ? extends V> valueSelector;
          final int bufferSize;
          final boolean delayError;
          final Map<Object, GroupedUnicast<K, V>> groups;
  
          static final Object NULL_KEY = new Object();
  
          Disposable s;
  
          final AtomicBoolean cancelled = new AtomicBoolean();
  
          public GroupByObserver(Observer<? super GroupedObservable<K, V>> actual, Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector, int bufferSize, boolean delayError) {
              this.actual = actual;
              this.keySelector = keySelector;
              this.valueSelector = valueSelector;
              this.bufferSize = bufferSize;
              this.delayError = delayError;
              this.groups = new ConcurrentHashMap<Object, GroupedUnicast<K, V>>();
              this.lazySet(1);
          }
  
          @Override
          public void onSubscribe(Disposable s) {
              if (DisposableHelper.validate(this.s, s)) {
                  this.s = s;
                  actual.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              K key;
              try {
                  key = keySelector.apply(t);
              } catch (Throwable e) {
                  Exceptions.throwIfFatal(e);
                  s.dispose();
                  onError(e);
                  return;
              }
  
              Object mapKey = key != null ? key : NULL_KEY;
              GroupedUnicast<K, V> group = groups.get(mapKey);
              if (group == null) {
                  // if the main has been cancelled, stop creating groups
                  // and skip this value
                  if (cancelled.get()) {
                      return;
                  }
  
                  group = GroupedUnicast.createWith(key, bufferSize, this, delayError);
                  groups.put(mapKey, group);
  
                  getAndIncrement();
  
                  actual.onNext(group);
              }
  
              V v;
              try {
                  v = ObjectHelper.requireNonNull(valueSelector.apply(t), "The value supplied is null");
              } catch (Throwable e) {
                  Exceptions.throwIfFatal(e);
                  s.dispose();
                  onError(e);
                  return;
              }
  
              group.onNext(v);
          }
  
          @Override
          public void onError(Throwable t) {
              List<GroupedUnicast<K, V>> list = new ArrayList<GroupedUnicast<K, V>>(groups.values());
              groups.clear();
  
              for (GroupedUnicast<K, V> e : list) {
                  e.onError(t);
              }
  
              actual.onError(t);
          }
  
          @Override
          public void onComplete() {
              List<GroupedUnicast<K, V>> list = new ArrayList<GroupedUnicast<K, V>>(groups.values());
              groups.clear();
  
              for (GroupedUnicast<K, V> e : list) {
                  e.onComplete();
              }
  
              actual.onComplete();
          }
  
          @Override
          public void dispose() {
              // cancelling the main source means we don't want any more groups
              // but running groups still require new values
              if (cancelled.compareAndSet(false, true)) {
                  if (decrementAndGet() == 0) {
                      s.dispose();
                  }
              }
          }
  
          @Override
          public boolean isDisposed() {
              return cancelled.get();
          }
  
          public void cancel(K key) {
              Object mapKey = key != null ? key : NULL_KEY;
              groups.remove(mapKey);
              if (decrementAndGet() == 0) {
                  s.dispose();
              }
          }
      }
  
      static final class GroupedUnicast<K, T> extends GroupedObservable<K, T> {
  
          final State<T, K> state;
  
          public static <T, K> GroupedUnicast<K, T> createWith(K key, int bufferSize, GroupByObserver<?, K, T> parent, boolean delayError) {
              State<T, K> state = new State<T, K>(bufferSize, parent, key, delayError);
              return new GroupedUnicast<K, T>(key, state);
          }
  
          protected GroupedUnicast(K key, State<T, K> state) {
              super(key);
              this.state = state;
          }
  
          @Override
          protected void subscribeActual(Observer<? super T> observer) {
              state.subscribe(observer);
          }
  
          public void onNext(T t) {
              state.onNext(t);
          }
  
          public void onError(Throwable e) {
              state.onError(e);
          }
  
          public void onComplete() {
              state.onComplete();
          }
      }
  
      static final class State<T, K> extends AtomicInteger implements Disposable, ObservableSource<T> {
  
          private static final long serialVersionUID = -3852313036005250360L;
  
          final K key;
          final SpscLinkedArrayQueue<T> queue;
          final GroupByObserver<?, K, T> parent;
          final boolean delayError;
  
          volatile boolean done;
          Throwable error;
  
          final AtomicBoolean cancelled = new AtomicBoolean();
  
          final AtomicBoolean once = new AtomicBoolean();
  
          final AtomicReference<Observer<? super T>> actual = new AtomicReference<Observer<? super T>>();
  
          State(int bufferSize, GroupByObserver<?, K, T> parent, K key, boolean delayError) {
              this.queue = new SpscLinkedArrayQueue<T>(bufferSize);
              this.parent = parent;
              this.key = key;
              this.delayError = delayError;
          }
  
          @Override
          public void dispose() {
              if (cancelled.compareAndSet(false, true)) {
                  if (getAndIncrement() == 0) {
                      actual.lazySet(null);
                      parent.cancel(key);
                  }
              }
          }
  
          @Override
          public boolean isDisposed() {
              return cancelled.get();
          }
  
          @Override
          public void subscribe(Observer<? super T> s) {
              if (once.compareAndSet(false, true)) {
                  s.onSubscribe(this);
                  actual.lazySet(s);
                  if (cancelled.get()) {
                      actual.lazySet(null);
                  } else {
                      drain();
                  }
              } else {
                  EmptyDisposable.error(new IllegalStateException("Only one Observer allowed!"), s);
              }
          }
  
          public void onNext(T t) {
              queue.offer(t);
              drain();
          }
  
          public void onError(Throwable e) {
              error = e;
              done = true;
              drain();
          }
  
          public void onComplete() {
              done = true;
              drain();
          }
  
          void drain() {
              if (getAndIncrement() != 0) {
                  return;
              }
              int missed = 1;
  
              final SpscLinkedArrayQueue<T> q = queue;
              final boolean delayError = this.delayError;
              Observer<? super T> a = actual.get();
              for (;;) {
                  if (a != null) {
                      for (;;) {
                          boolean d = done;
                          T v = q.poll();
                          boolean empty = v == null;
  
                          if (checkTerminated(d, empty, a, delayError)) {
                              return;
                          }
  
                          if (empty) {
                              break;
                          }
  
                          a.onNext(v);
                      }
                  }
  
                  missed = addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
                  if (a == null) {
                      a = actual.get();
                  }
              }
          }
  
          boolean checkTerminated(boolean d, boolean empty, Observer<? super T> a, boolean delayError) {
              if (cancelled.get()) {
                  queue.clear();
                  parent.cancel(key);
                  actual.lazySet(null);
                  return true;
              }
  
              if (d) {
                  if (delayError) {
                      if (empty) {
                          Throwable e = error;
                          actual.lazySet(null);
                          if (e != null) {
                              a.onError(e);
                          } else {
                              a.onComplete();
                          }
                          return true;
                      }
                  } else {
                      Throwable e = error;
                      if (e != null) {
                          queue.clear();
                          actual.lazySet(null);
                          a.onError(e);
                          return true;
                      } else
                      if (empty) {
                          actual.lazySet(null);
                          a.onComplete();
                          return true;
                      }
                  }
              }
  
              return false;
          }
      }
  }
  